Flexible panel form for thin shells



Dec. 22, 1964 P. GRAHAM 3,161,938

FLEXIBLE PANEL FORM FOR THIN sHELLs Filed Feb. 2, 1961 2 Sheets-Sheet. l

TORNEY Dec- 22, 1964 P. GRAHAM 3,161,938

FLEXIBLE PANEL FORM FoR THIN sHFLLs Filed Feb. 2, 1961 l:e sheets-sheet 2 INVENTOR.

TToRNEY United States Patent O 3,161,938 FLEXBSLE PANEL EGEM FUR 'HHN SHELLS Phillip @rali-am, 2&25 Glenmore Ave., Pittsburgh, Pa. Filed Feb. 2, 1961, Ser. No. 86,814 2 Claims. (Cl. 25-121) This invention relates to improvements in flexible form for molding thin shell building panels, including adjustable exible elastic edge forms which can be used to cast curved and fiat, thin shell, reinforced panel sections of cernentitious materials and plastics, which panel sections can be readily interlocked or bonded together to obtain an integral building shell of great strength. This invention is a continuation-in-part of my copending application, Serial No. 785,273, now Patent No. 2,971,237, tiled January 6, 1959, entitled Flexible Building Panel Form.

This invention particularly refers to adjustable forming means that has durable elastic flexible edge forms that allow low cost, quick and accurate molding of various shapes and sizes of curved and flat, precast, prestressed, reinforced thin shell concrete panel sections. The forming means allows the molding of panel sections that are suitable for use to speadily construct low cost, pleasingly attractive, blast resistant, corrugated shelled houses and other buildings above or below ground. rl`he shapes of these precast panels make such structures stronger and more durable than other types of buildings using equal amounts of material, so as to provide security shelters for the occupants against the territlcally violent forces of atomic and H-blasts (in fringe arcas), as well as other violent forces, such as those from hurricane-like winds, earthquakes, explosions, floods, avalanches, and lires.

My co-pending application Serial No. 785,273 shows how panels formed with such lexible forms can be used to build shelters; in addition, the co-pending application lists my numerous related patents that supplement the flexible form means in building shelters.

The form means allows multiple curved thin shell, precast panels to be molded accurately at low cost. The form means allows accurate positioning of fastening means along the edges of the panels so the panels can be quickly and securely joined at erection. This fastening means allows precast sections to be erected dry with pins during inclement weather-grout mortar being inserted in the joints at a later suitable period. Very little labor is required to make and erect the panels, due to the eilciency of the form means. Unskilled labor can make and erect the panels since the form means is nearly fool-proof.

The elastic edge forms can be used many times to mold many differently shaped panels without materially deteriorating. Non-elastic panel portions of the form means can be made of concrete; they can be used to mold the curved faces of the precast building panels, such concrete panel forms may be used as building panels after they have outlived their usefulness as forms.

The form means embodied in this invention is animprovernent over the form means described in my copending application Serial No. 785,273, since it is simpler, easier to use, and it allows reinforcing strands to be positioned faster. T he improvements include semi-tix pin means on the support fasteners to allow the reinforcing strands to be easily coupled and uncoupled quickly, thereby eliminating a fault of the form means shown in my copendng application Serial No. 785,273. The improved plastic edge form strip have transverse slits from the spaced holes to the bottom or top of the strip to allow the elastic strip to be positioned after metal support fastener means and concrete reinforcing strands are accurately positioned, thus the plastic strip may be kept in a locked compartment before use and be inserted quickly in an assembly just before pouring the concrete, thereby allowing vandals little time to damage or steal the plastic.

lbld Patented Dec. 22, i964 ICC The shortening of the period of use of the elastic form to form a panel edging allows the elastic form to be used more often to keep operating costs low. The slits also allow the edge form and cured precast building panel to be removed from their engagement with the support fasteners without objectionably disturbing the support fasteners and the base to which they are spaced. Furthermore, the slits allow the elastic form to ybe pried loose and pulled free of a semi-cured panel edging after molding it, allowing the reinforcing strands to remain connected to support fasteners and thus remain pretensioned while the concrete cures, thereby removing the elastic strip so vandals cannot damage it and allowing the concrete edging to be exposed for curing.

An object of my invention is to provide an efficient curvable, elastic, flexible, plastic edge form strip that is able to accurately mold the edges of straight and curved, reinforced thin shell precast cernentitious sections ot' various suitable widths, lengths and thicknesses, including tapered thicknesses; furthermore, to provide means to position and prestress the reinforcing, also means to quickly and accurately position connectors on the ends of the reinforcing.

Another object is to provide a more eicient curvable, flexible rubber-like plastic edge form strip that is superimposed onto a base form consisting of a similar elastic edge form that is securely bonded to the edge of a cementitious reinforced form panel to accurately mold the bottom and the edge of a precast concrete building panel that is like the form panel.

Other objects of my invention will become more apparent from the following description taken with the accompanying drawings wherein:

FIG. l is a plan view showing flexible forms being used to mold thin multiple curved reinforced concrete sections;

FG. 2 is a sectional View taken along line 21-2 of FIG. 1;

FIG. 3 is a sectional View taken along line 33 of FIG. 1; 4

FIG. 4 is an enlarged, fragmentary sectional view taken along line 4-l of FIG. 1;

FlG. 5 is an enlarged, fragmentary sectional view takenv along line 5--5 of FIG. 1;

FG. 6 is an enlarged, cross-sectional view taken through an unrestrained, elastic `ilexible edge form and spacer strand;

FIG. 7 is a fragmentary elevational View showing modular spaced holes and slits in the elastic edge form;

FIG. 8 is an enlarged, fragmentary elevational view taken along line -S of FIG. 1;

FIG. 9 is an enlarged, fragmentary, sectional View taken along lines 9 9 of FIGS. 1 and 8;

FlG. 10 is a fragmentary, sectional view taken along line lil-lll of FlG. 8;

FlG. 11 is a fragmentary, sectional View taken along line ll-ll of FlG. 8;

FIG. 12 is a fragmentary, sectional View taken along line 12s-12 of FIG. 10;

FIG. 13 is a fragmentary plan view showing details of the spacer strand;

FG. 14 is a fragmentary plan view showing details of the pin and bolt assembly; y

FlG. 15 is a fragmentary View similar to FIG. 9, showing a non-yieldable mounting of a bolt on a support fastener;

FIG. 16 is an exploded, perspective view showing details of a metal reinforcing strand;

FIG. 17- is a fragmentary, sectional view similar to FIG. 9, showing an arrangement for molding a panel which has modified reinforcing;

FIG. 18 is an isometric view showing details ofthe 3 modified reinforcing for use in the arrangement shown in FIG. 17.

Referring to the drawings, FIGS. l to 4 inclusive show assemblies F1, F2, F3, and F4 in an arrangement for molding crescent-like shaped, two-way curved dished or corrugated precast, prestressed, reinforced concrete panel sections 1. The assemblies are stacked on the base form 2. The assemblies F1, F2, F3, and F4 will be identical after the casting operations have been completed. The space 1b in assembly F3 illustrates the typical shape to be lled with concrete to mold a panel like panel 1. The assembly F1 would have such a space 1b before a panel 1 is formed in it.

FIGS. 5 to 16 inclusive show details of an assembly F1 Iand the like. These intricately shaped panels 1 can be accurately molded at low cost with little effort due to the flexible adjustable elastic Iand resilient plastic or rubber edge form strip 3. The forms 3 are the edge moldings of the assemblies. An assembly may be stripped of its form 3 so the panel 1 may be used as a building panel. An assembly may also be kept with its form 3 intact with the panel 1, so the assembly may be used as a form until the panel portion deteriorates from usage or is no longer needed as a form, then the panel l may be used as a building panel. The stacked casting means allows the molding of accurate duplications of an intricately curved panel surface such as that of the base form 2 and a panel l. A panel 1 for use as a portion of an additional form assembly may be molded on the form 2. The top surface of the panel 1 may be shaped with a screed or scraper.

When an original curved surface of the base form 2 is made, it may be duplicated in reverse by casting a female form on it, thus obtaining male and female forms which may be used'to mold additional forms or building panels. The lower facing of a panel 1 is usable as a female form.

intricately curved form assemblies with their elastic edging strips secured to the concrete panel form may be used as seed-like means to reproduce duplicatepanel sections at a very low cost yas compared to other casting methods.

The casting means shown causes the molding of identi- Cal curvatures to the surfaces of the panel faces, except that the top surface of the panel is convex and bottom surface is concave. The width contour of a panel Ll has equal radii but with different centers spaced vertically. The side edge radii are identical. The identical curvature of the faces of each panel allows identically curved building panels to be laminated to each other where Vadditional building shell sections is required for strength or insulation.

FIG. 2 shows the standard curvature across the width of panels 1. Curved panels four feet wide across the chord are the standard use for the example shown as it is suitable for constructing small buildings. Other standard widths of panels and other curvatures may be used, including those varying the width curvature to obtain' deeper corrugations and corrugations that are tapered in depth. While I have described the curvatures as arcuatej they also may be made with irregular curves.

vThe identically shaped panels 1 allow low cost casting,

Ylowcost handling, and low cost storage, since they can be'nested ltightly together to conserve space, also because the panels are light in weight. When the cured curved panels are nested together, they have little tendency to bend and break during shipping and handling because the curved panel shape is very strong, and a stack of the curved panels acts as a strong unit.

Form assemblies whose panel sections l are to'be used as building panels may be kept intact in stacks so the assemblies are fastened together for safety and ease in handling as a unit during shipping and storage; furthermore the forms 3 protectthe fragile 'concrete' edges and the reinforcing connections from being damaged, The

form 3 also shields the panel edges from mud, ice and other objectionable elements.

This method Iof stacking forms in tiers and casting leaves less chance of errors in making duplicate panels. The stacking method requires little space for casting and curing, and it allows the forms to be set up quickly with unskilled labor.

The base form 2 may be made of concrete, plaster, or other suitable materials. Materials other than concrete may be used for panel portions of the form assemblies. These materials include plaster, metal, and wood.

Concrete panel surfaces to be used for molding should -be coated or covered with a non-adhering substance to prevent fresh concrete from adhering to them. The base form 2 has anchored to it template bar forms 2a, 2b, and 2c. The template bars may be fastened together to form a frame. The base 2 is anchored to the base plate 2d.` The arrangement of the base 2 on the base plate 2d is a simple means to support the forms for casting, lt allows the casting means Ito be portable. The Whole assembly may be suitably tilted, or be mounted vertically, While casting to insure against voids forming in the side surfaces of the concrete panels, by diverting air pockets to edges Where they can be eliminated or be compensated for with more grouting in the field joint.

The template bars 2a, 2b and 2c have accurately spaced holes that are used to align and hold the support fasteners B of the assembly Fl to the base 2. These template bars are a means to accurately and quickly position the support fasteners B. The short template bars 2b and 2c would likely be used repeatedly as a standard for making similar panels that vary in length and longitudinal curvature, therefore they would be practical. The long curved template bars 2a would be practical if used frequently. The template bars could be bent at low cost. The template bars may be omitted if it is preferred to fasten the assembly F1 direct to the base 2, with bolts penetrating the base to hold the assembly.

When thick template bars are notused, threaded metal inserts such as shown in FIG. 17 may be used. The inserts would be embedded in the concrete of base 2 to which the support fasteners may be bolted. Thin and limber template bars may be used, particularly to space metal inserts.

The concrete for panel 1 of the assembly Ft can be poured Within the confines of form 3 with the top surface 4of the Vpanel being leveled with a screed, or the top surface may be molded by placing a completed assembly F2 on top of the assembly F1. When the top surface of a panel 1 is to be shaped with a screed, the top portion of the form 3 may be depressed with a top member template bar, similar to the arrangement shown in FIG, 17.

The form 3 and supplementary metal parts can be positioned to allow them to be used to mold concrete panels of various widths and various lengths in multiples of eight inch or other suitable modular units, also in various curvatures as well as flat shapes; furthermore, the

panels can be molded in various thickness with the form 3. The form 3 and its supplementary parts may be arranged for molding non-rectangular panels such as curved or llat segmental panels'and curved or flat round panels, The form 3 maybe compressed to taper it to allow it to mold a tapered panel. The form 3 may be compressed to allow a range of depths for molding panels of suitable thicknesses for thin shell building construction. For example, a form 3 with an unrestrained depth of two and a. quarter inches that may be compressed to one and a half inches, wouldrallow its use in molding a wide range of panels. ,Smaller and larger sized forms 3 may be made, such yas smaller sizes for very thin type panels that are to be laminated,

vA panel of double thickness may be cast Within the confines of the edge forms of assemblies FZ-and F3. A panel of triple thickneses maybe cast within the coniines of the edge forms 3 of assemblies F1, F2,'and F3. Such thick panels, particularly dat panels, would usually need the reinforcing near each face to resist bending forces. The triple thick panel would usually not have reinforcing within its center portion that is molded by the assembly F2. The two grid systems of a thick panel may be tied to each other with short metal strands.

There is accurate modular spacing means for spacing stili embeddable reinforcing strand rods or wires 4. There are stiff connector means for connecting the reinforcing strands 4 to the support fasteners B. A strand 4 has a connector welded to each end, the connectors being an eyelet or eye connector da on one end and a clevis connector 4b on the other end, as shown in FIG. 16. The connectors da and 4b are means to anchor the strand 4. The connectors @.-rz and Lib provide a clevislike pin connected interlocking means for joining building panels to each other at erection.

Each end of each strand 4 may have an eye da if preferred. A pair of eyes 4a would be joined at erection with a bolt. The bolt would act in single shear, thus being less foolproof panels may be made with all of the endsof the wires Lihaving eyes 4a and clevises 4b spaced alternately around the periphery of the panel.

A modular unit is used for spacing the reinforcing strands 4 and for sizing of the panel. With this modular system, the reinforcing spacings are standardized for various types of construction on which it is to be used. The standard module for spacing the reinforcing for the examples shown is eight inches. When thin shell panels are to be used for non-arched spans, a smaller module for the metal reinforcing spacing may be used since closer spacing would prevent objectionable cracking of the concrete and would resist the tension forces. When closer reinforcing spacing is required, the module may be four inches. A form means with a four inches module may be used. lt would allow desirable combinations, such as eight, twelve, and sixteen inches, by plugging the spaced holes in the form 3 that are not in use. Such skipping of holes would be done when it is preferred to use wire mesh to control the shrinkage cracks and to use a few wires 4 where reinforcing is needed to resist larger tension forces. Onlya half module space is used from the corners of the panel l and the like to the lirst uniformly spaced reinforcing strand so that when erected, half module spaces on adjoining panels form a whole module space. v This feature allows an intermediate edge portion of a panel to straddle the end of a joint.

The edge form 3 may be made at low cost with a continuous extrusion process. The spaced holes 3g for the reinforcing strands 4 may then be punched through the forni 3 as shown in FiG. 7 After the holes 3g are punched, the form 3 may be slit with a knife to forrn transverse slits 3f. The slits 3f are cut from the holes 3g to the bottom of the form 3. This method of manuacturing by extrusion allows a standard blank form 3 to be punched and slit to suit different modules, including those spaced in inches and those spaced to a metric system module.

The edge form 3 is elastic to allow it to be depressed, bent, curved, or twisted to mold various shaped panels. The form 3 for the assembly Fl and the like is slit and bent at three or" the corners. An end of the form S is coped to allow it to be tightly tted to an intermediate portion of the form strand to close or encase a space for casting a panel. a hook (not shown) securely attached to it. The hook may be pointed to allow it to pierce the portion of the form 3 where the form is joined to encase a space. Hooks The spacer wire 5 at an end of the form 3 has i Cil allow a ready means of coupling and uncoupling portions of a form strand. Pieces of form 3 may be readily hooked together to make any length of form strand desired. Splicing means for a form assembly is described and shown in my co-pending application Serial No. 785,273.

The elastic form 3 can yield slightly to break its bonding elect to the cured concrete. The non-depressed shape of the form 3 is shown in FlG. 6. The form 3 may have longitudinal holes 3c, 3d, and 3e. The forni 3 may be made of elastic plactic that is stii enough so the upper portion of the ferm will not sag from its own weight. The form 3 may be made of a more elastic, weaker plastic that is reinforced with fabric or with spring steel wire 3k. The wire 3k may be continuous with loops in the upper and lower portions. When the form 3 does not have the modular spaced slits 3,the form may be thin, with the holes 3c and Sd'being airtight allowing the forni to be inllated to stillen it. The elasticity of form 3 tends to cause the form to seal its contact surfaces with the abutting form 3 of the adjacent assembly, also its contact surfaces which engage template bar forms 2a, 2b, and 2c.

Most of the panel sections to be cast require keying grooves in all their edges, so that panels can be keyed together with mortar grout at the time of erection. The form 3 has a protruding medial portion which is the groove mold olfset 3a. Modified form sections, similar to form 3 but with a smaller groove mold offset 3a or no groove mold, may be made so they can be readily spliced to other torni sections when needed. An edge form without an offs-et 3a is useful for molding a precast panel edging that is to form a portion of the edging at an opening for a window that does not require a groove; such a window suitable for use with the thin shell panels is shown in my Patent No. Des. l9l,302, entitled Curved Jalousie Window.

Modied elastic forms (not shown) similar to forni 3 may include features o the forms described in my copending application Serial No. 785,273. Such moditica tions may include having the spacer strands embedded in the plastic.

The form 3 may have a retainer olset 3b, shown in FIGS. 5 and 6, to engage or catch against the spacer wires 5 and thus restrain the form 3 from tending to rise due to the lower portion of the form pressuring upwardly. The retainer oliset b may be spaced lug-like oisets instead or" a continuous offset. The offset 3b would be particularly useful when the form 3 has slits 3f; the slits 3f would otherwise broaden and allow the form 3 to rise unhampered by the reinforcing strands 1 and by the spacer strand M. The elastic form 3 may be stretched and compressed to pull it free of a semi-cured panel 3l, spacer strand M and reinforcing strands d.

The form 3 with slits 3f and otset 3b may be positioned on strands 4 a distance from the support fasteners B, then be slid into the position shown in FlG. 5, thereby allowing the oset 3b to be squeezed under the spacer wire 5. n

The spacer wires 5 are attached to the splice bars 6 by weldin g or by other suitable means to form an accurate pliable metal spacing strand M. The spacer strand M is positioned along the full length of the formstrip 3 at substantially the central portion of the form 3. The bars 6 are short steel bars with a hole in each. The bars 6 are accurately spacedva module apart to match the spacing of the holes 3g in the form 3..

Each support fastener B has a semi-hired vertical pin 7 attached to it by a bolt lil or a bolt ille. The bolt it) is shown in the arrangement in FIG. 9, which has a take-up means to tension the strand d. FlG. l5 shows a bolt iic that is tixed to accurately maintain a fixed setting for an end of a strand d. Bolts il@ are used along one side and one end of'forrn assembly F1 and the like. Bolts lille are used along the otherv side and other end of the form assembly. Each bolt itl and lille is threaded and jammed tightly to a vertical oiset on a pin 7. The clevises ab and the eyes da at the ends of the reinforcing strands 4 are forced down on the pins 7 to anchor the reinforcing strands 4 to the support fasteners B. The end of each pin '7 is pointed so it acts as a Wedge to force the clevis db, or the eye 4a, into position. Each pin 7 has a llat triangular shaped base portion as shown in FIG. 14. r[his dat base provides a seat for the connector da or 4b. The spacer strand M, formed by wires 5 and bars 6, maintains the modular spacing for the connectors da and 4b by the holes in bars 6 Aengaging the pins 7 and restraining the pins from moving laterally objectionably. Without the strand M, the pins 7 would tend to pivot laterally due to play in the connection between the support fastener B and the base 2. The spacer strand M also prevents the form 3 from stretching in length from the pressure of green concreteagainst it. The wires 5 are centered, thus the form 3 may be bent or twisted without objectionably varying the spacing of the holes 3g in the form. Panels of limited accuracy may be molded with forms 3 without the spacer strand M wires, the wires 4 being anchored to the pins 7. Support fasteners B may be positioned very accurately and securely to space the end connectors 4o and db of the reinforcing wires d, when spacer strand M is omitted.

There is a hole in each splice bar 6 to engage a pin 7 on a fastener B, to thus accurately position the clevises 4b and the eyes da. Since an eye da is thinner than a clevis 4b, an adapter 4p, shown in FIG. 16, is slid onto an eye da so the eye da is positioned and aligned properly. The clevises 4b and eyes ia are shown shouldered due to the long rectangular rod strand portions 4s being narrower than the main portions of the clevises and eyes, the wire e being welded to the stems. The strands is being strong resist forces caused by rough handling that tend to bend or twist the clevises and eyes out of alignment. rihe shoulders on the clevises and eyes are for allowing forked wedges to be driven between the cured concrete of the panel l and the main portions of these connectors 4a and lb to tension the strands 4. A mold S is shown temporarily cemented to the form 3 in FIGS. 9 and l0. panel l. The access holes allow forked wedges to be inserted and be driven between the cured concrete and the Wide shoulder portions of the connectors da and 4b. After curing the panel 1 and exposing its top surface, each mold 8 is gripped with tongs, pried loose and pulled free from the concrete and the form 3.

Each cleavis 4b and eye 4a is locked into position with respect to a pin 7'V and a spacer strand splice bar 6 by pushing the retractable spring lock 9 towards the strand 4i; the lock S9 clamps the parts together. A lock S3 is shaped so it restrains a clevis 4b or eye 4a along with the engaged bar 'd from tilting or disengaging from the pins '7. A lock 9 is retracted by sliding it on bolt lil or bolt 10c.

Each bolt l@ and ltlc may be turned to unthread it to disengage it from a pin 7 so it may be retracted from the recess in the form 3. The bolts lil and 10c may be retracted to provide more clearance to allow the'panel and the attached form 3 to be lifted from the connes of the fasteners B without disturbing the remaining portions of the fasteners. The pins 7, locks 9, and spacer strands M would remain engaged to connectors 4a and 4b.v Thus partial assembly set-ups including support fasteners B may be maintained to allow low cost duplicationV in molding panels.

When the cured panel 1 is to be removed from engagement tothe base 2 and the support fasteners B, the bolts lil and libc are turned to disengage and retract the bolts from the pins 7. The locks 9 may remain in locked position to hold the pins 7 to thev spacer strandgM and tothe connectors and 4b, therebyV retaining the form 3 around the periphery :of the panel l so the form 3 canV protect the panel edge during shipping and storage.

Molds are used to form access holes in the Y When a serni-cured panel l is to be allowed to cure for a long period, locks 9 may be retracted to allow the bars 6 of the spacer strand M to be lifted and disengaged from pins 7. Then the locks may be pushed back to relock the connectors la and 4b to the pins 7. After relocking, the spacer strand M and the strip 3 may be pulled free so they may be used to mold other panels. This means also allows the reinforcing strands 4 to remain tensioned while curing.

Modified pins similar to pin 7 may be bent back slightly toward the bolt 1d or 149e to form a slight hook to which connectors tu and 4b may be coupled. The slight hook would restrain highly tensioned strands l from uncoupling. The hooked pins would not Vrequire locks 9.

Since the bolts ltlc are non-yielding and the ends of the strands 4 are fixed along one side and one end of an assembly F1 and the like, the strands 4 may be pretensioned without pulling the eyes 4a and the clevises 4b out of alignment. The bolts It() may be moved laterally by rotating nuts ltlb to take up slack and tension the reinforcing strands 4. A spring 1l may be mounted on each bolt lll to maintain the pretensioning. Thus slight yielding of a support fastener B will not cause a strand 4 to lose its tensioning. Springs 1l would be decompressed to allow the adjacent connector la or 4b to be coupled to the adjacent pin '7. A nut alla may be used on each bolt lll to limit the pull on the strand d so as not to pull the Whole strand out of alignment or break it. Each nut 10b can be turned to decrease the tension on each spring 11 while coupling a connector to a pin 7, then the nut lill: can be reversed to selectively compress they spring ll to selectively pretension the strand 4. The nuts tlb may be turned to pretension the strands it, omitting the springs l1. A bolt lll has a head which may be gripped with a wrench to hold the bolt while tightening the nut lob. The nut lila on bolt lilo may be used to help set the bolt ltlc rigidly so the pin 7 is maintained in proper position,` also to restrain the bolt Mic from tilting When'the strand 4 is sloping such as for the condition shown in FIG. 4. The nuts 16a may be omitted if spacer strands M are used and kept taut. When the spacer strand M is taut, it helps to restrain the pin 7 and the connector 4a or 4b to which it is locked from tilting out of alignment. Nuts 1.641 and ltlb may be self-locking nuts,.so they will not loosen from vibration.

Prestressing is the term used alternately when referring to pretensioning reinforcing before the loads are applied which the concrete section is to carry. The tensioning straightens the reinforcing strands 4 and then stretches the metal slightly. Therefore when loads tend to bend such a prestressed panel l, Vthere is no slack to take up in the reinforcing 4; the pretensioned strands 4 act irnmediatelyto resist tensional stresses. The simple pretensioning take-up means of spring 11 and nut 10b may be used aiongwith conventional preped iron particles in the concrete mix. The iron oxidizes and expands to compensate for the normal shrinkage of the concrete, thus the concrete cannot shrink and force the strands 4 to shrink.

Pretensioning or so-called prestressingfor use with this type `of form means is described in my cts-pending application Serial No. 785,273. Y

The panels 1 may be made without prestressing the wires 4. Such panels would be suitable for much construction Work, `particularly when the panels are to be used in aroh construction and there is little or no tension stresses. Vlire meshor fabric 12 may be stretched and attached to the wires 4, as shown in PIG. 1. The mesh 12 would be highly suitable for use in nonpre'stressed panels. The mesh V12 would control the shrinkage cracks and cracks from expansion and contractions, causing the cracks to be small.

Curved wires 4h, shown in FlG. l, may be tied to wires 4 and support fasteners B. The wires 4h may be lock Washers under the heads of the screws 2l.

9 pretensioned with the support fasteners B and/ or resilient chairs.

The length of reinforcing surands 4 for flat panels and for those spanning the width of panels l are made in the modular multiples of eight inches to conform to the standard module established. The distance between centers of connector holes or" a reinforcing strand 4 is made accurate. The longitudinal wires d on the panels l vary in length due to their various longitudinal radii which step up from the side edges where the modular spacing of the side connections is eight inches. The various longitudinal wires 4 of the panel i may be different in size and/or composition to allow them to take the ditferent degrees of stress to which they would be subjected. Corrugated panels like panels 1 may have additional longitudinal wires 4 spaced with closer modules, such as four inch modules, near the side edges of the panel and/or at the center portion of the panel to cause the reinforcing to work more effectively to resist forces tending to bend the panel.

When the curved wires i are positioned above the base 2 or above the convex surface of a cured form panel l, they may be supported by the chairs i3. The straight portions of taut longitudinal wires i do not require chairs 13. rl`he chairs i3 may be resilient to cause them to pressure the wires e to eliminate slack and thereby tighten and pretension the wires. This means to pretension the wires i may be used without a take-up nut ltlb on bolt Mi or spring ll. Non-resilient chairs 13 may be wedged under wires d to eliminate slackand thus pretension the wires.

As shown in FlG. 4 in the assembly F3, the oifset 3a on form 3 yields by stretching upwardly due to the angui lar position of the reinforcing strand Chairs lll which are similar to chairs 13 are positioned to bear against the offset 3a to eliminate any downward bulging of the form 3. There is a thin lower lip of the panel below the oifset 3a. lt is relatively weak in its resistance to breakage from rough handling, so reinforcing wire l5 is positioned in this space to eliminate breakage.

The support fasteners B have means to provide various functions in addition to the functions previously described. The support fasteners B are used to selectively gauge the effective depth of the form 3 and thus the thickness of the panel l. The fasteners B restrain the form 3 from tilting. The support fasteners B align and support the assemblies F1, F2, F3, and F4 with the template bars 2a, 2b, and 2c. Details of a fastener B are shown in FIGS. 8 to l5 inclusive.

A fastener B has a lower vertical rigid tube lr6. The tube 16 has a base plate i7 welded to it. A beveled washer l is engaged to the template bar 2b and the plate i7. Beveled washers i3 are used for curved conditions such as that shown in FlG. 8. A rigid upper tube 19 has a slidable engagement with the upper portion of the tube 1.6. The tube i9 has a cap 2li welded to it. The Sides of the tube i6 have spaced notches in slots to allow machine screws 2l to project into threaded ilanged holes in the tube l?. The tubes lo and 19 are telescoped to allow them to slide to adjust their combined overall height.

After the fasteners B are adjusted, the screws 2l are inserted and tightened to maintain the setting. There are The base plate 17 and the washer le are fastened to the template bar 2b with a bolt 23 and a lock washer. 23 may also be usedgto position the plate 17 to the template bar 2b. ri`he dowel 23 is bolted to the plate 17. The inverted countersunk head of the dowel 23 engages the underside of the plate i7. The plain dowel shank projects below the head. Bolts 22 may be used to attach and align the fasteners B ofthe assembly Fl to the fasteners B of the assembly FZ. Dowels 23 align the upper and lower fasteners B. The pointed dowelsiZS are self-centering with the holes in the adjacent form A dowelL assembly. A bolt 1li projects through one of the spaced notches in the slots in the tubes 16 and 19. The bolts 10 and idc can be adjustably set in height to suit the required elevation for the wires 4. The Wiresl are positioned below the center of a hat precast floor panel to efficiently use the wire for resisting tension. The notched slots in the tubes 16 and 19 that engage the bolts lll and -ltlc and the notched slots in tubes ld that engage the screws 2l may be filed to length notches when adjusting means requires intermediate non-notched positioning.

As shown in FIG. 17, wire mesh fabric 27 may be used for reinforcing rather than wires 4.

Reinforcing rod anchors Z6 are welded to the embeddable strand portions ls of clevises 4b and eye 4a. FIG. 18 shows an anchor 26 that is welded to a clevis 4b. The wire fabric 27 may be stretched and be fastened to the anchors 2o, then the support fasteners B may be used to pretension the fabric 27. Conventional Wire fabric 27 is suitable as reinforcing for flat panels or panels that are only curved in one direction. With this arrangement, shown in FIG. 17, each strong clevis 4b and each strong eye la act for many small strands of the fabric 27 to allow the reinforcing to act eliiciently like the reinforcing strands flact. i

Fiber glass may be embedded in the concrete for reinforcing and/ or insulation in an arrangement such as that shown in FlG. 17.

Tapered metal inserts such as insert 2S, shown in FIG. l7, may be used to fasten support fasteners B to the base 2f or the like. Still' top member template bars such as bar 29, shown in lllG. 17, may be used to help keep the support fasteners in alignment and to compress the form 3.

Washer 25 may be tack Welded to the tube 16 to maintain a temporary elevated position for a bolt. Temporary form connections and settings may be made in general with tack welds rather than the bolts, nuts, screws, and dowels. Non-adjustable support fasteners may be made by permanently welding parts together.

After a panel has cured to an extent in the assembly F3, the assembly F4 may be raised slightly to create a gap between the assemblies. AThe nuts on the bolts 22 would be loosened so the assemblies may be wedged or jacked apart. The dowels 23 and the bolts 22 would hold the two assemblies in alignment. The gap between the assemblies allows the surface of the curing panel to be reached by steam and air while curing.

When the form assemblies are used to mold panels that are tapered in thickness, the form assemblies used to mold the top and bottom surlaces of the tapered panel are variably spread apart, the form 3 being depressed to a tapered shape. The fasteners B would be suitably adjusted lto support the tilted form assemblies to maintain the selective variable thicknesses due to the tilting.

The fluid concrete for a panel l may be inserted into a form assembly by various means. The concrete may be inserted through the access holes lc that are cored in the panels ll. Concrete can be deposited within the confines of the form 3 of an assembly before a complete form assembly is used to cap the uid concrete. Theexcess concrete is forced out of the holes 1c. The holes lc may also be used for inserting vibrators. Ari access unit for inserting concrete through the elastic form means is described in my co-pending application Serial No. 785,273. j

In a typical joint of the interlocked panels like panel 1, a pin or bolt connects each eye da to a clevis 4b. The panels l are keyed together with the grout mortar. A. panel similar to panel il may be molded with only a portion of the panel edging being molded with elastic form 3. rThe other portion of the panel edging'rnay be molded by other suitable form means, includingfedges of like vpanels that are positioned alongside the space forl molding a panelso as to mold the edging. The use of edges of one or more cured panels as form means for' molding a portion of the edging of a panel similar to panel 1 allows panels to be precast or be cast in place against the edges of cured panels to which they are to be permanently connected when cast, or be permanently connected when rejoined at erection. 'Ihis casting means causes the panel edges that are to be joined to match; thus, in the panel to be cast, the ends of embeddable strands, such as strands 4 or anchor type strands 26, are spaced to suit slight inaccuracies in the positions off the ends of the embeddable strands in the cured panels. The ends of the embeddable strands, such as the clevises 4b and eyes 4a, in the cured panels may be positioned slightly inaccurately due to the fastener means being positioned inaccurately.

A very large panel may be cast by casting the panel in suitable portions. A large panel may be made with a series of panels similar to panel 1 being positioned side by side and having their edges joined with metal connector means and by bonding the cementitious edge portionstogether. Such a large panel can be erected by conventional tilt-up means or be lifted with a large crane.

When conditions do not allow the use of a large crane or shipment of a very large panel, a series of panels similar to panel 1 may be cast while joined to each other with metal connector means such as clevises 4b and eyes 4a. One cured panel may have other panels cast while joined to each of its side edges, or a panel may be molded between two like panels that areipositioned alongside of it in edge to edge relationship so as to dene the edges. Connector means on the cured panels would sup-V port the connector means for the panel to be cast that are joined to them, thus eliminating the fasteners B for such conditions.

When the panels are to be disengaged for shipment, the edging may have keying grooves molded in the panel edging. The keying grooves may be molded with elastic strip 3 that is squeezed into the groove in the cured panel edging, or other suitable means may be used, such as trimming od portions oi the form 3 that project outwardly from'the pins 7 and the panel to be cast.

lli)

When large door areas are to be cast in portions, they Y may be made by casting one or more panels having edging and embeddable metal strands like panel 1'. Additional panels would be cast adjacent the edges of the cured panels. The cured panels would support the embeddable metal strands of the panels to be cast and would key the panel edging into the keying grooves in the edging of the cured panels. This casting means eliminates the need of form 3 between the cured and uncured panels. In additiomithis casting means eliminates the need to grout the joints. The edges to be'forrned that are not dened by the edging of cured panels would be molded with strips of form 3 that are positioned by fasteners B. Strips of form 3 may be cut in standard lengths for standard Widths of panels and for standard lengths of panels and be positioned end to end at corners rather than be bent at the corners as shown in FIG. 1. Such short strips are suitable for use when one or more edges of a panel to be cast are defined by being positioned against edging of one or more `cured panels.

- My co-pending application Serial No. 785,273 describes further details pertaining to the usefulness of the forms, particularly as to the laccuracy of the form means allowing low cost erection due to accurate spacing and aligning of the holes of the connectors, enabling easy' and quick insertion of clevis pins and the grou-ting ofthe Vjointl later, also means toallow the elastic form 3 to be stakedwto the vground and be used to mold the edging of panels that are molded on their underside by soil.

Thus it will be seen that ,I have provided economical building form means tha-t Ais capable of performing a wide variety/"of operations to suit many conditions.

and modilications may be made within the contemplation of my invention and within the scope of the following claims.

l claim:

l. A form for molding at least a portion of a thin cemetitious building panel having still embeddable met-al strand means spaced along at least its edging, said form comprising an elongated elastic strip, a base for supporting said strip, said strip being suiiciently rigid so as to prevent sagging oi its top portion when supported on said base, said strip having an eilective height substantially equal to the thickness of said building panel portion to be cas-t, said strip having a length at least suliicient to mold said edging or" said building panel portion, said strip'being sufliciently ilexible so as to be bendable in all directions to allow it to follow the contours of curved and iiat planes, said strip having an offset portion substantially centrally of the height of said strip extending throughout its length and protruding inwardly towards the said building panel portion for molding a keying groove in said edging of said building panel portion, said strip coniinin 7 the fresh cementi-tious. aggregate of said panel portion deposited onto said base and deiining its shape, said strip having spaced transverse holes through an intermediate portion of its height and sub` stantially parallel to the plane of the said base, said embedded metal strand means of said building panel portion having end portions extending through said holes, and fastener means disposed along the length of said strip for fastening vsaid strip to said base and for anchoring the said end portions of said embeddable metal strand means, said strip having transverse slits extending from said spaced transverse holes to an edge of the said strip, whereby said strip may be positioned to mold said building panel portion after said end portions oi said embeddable metal strand means have been anchored to said fastener means, and whereby said strip may be remo-ved from engagement with said building panel portion without disturbing said embeddable metal strand means while said building panel portion is semi-cured to thus shorten the period of use of said strip to mold said edging of said building panel portion and to maintain the said end portions in position while said building panel portion cures, wherein said fastener means includes pin means supported thereon, said end portions of said embeddable metal strand means of said building panel portion include connector means, said connector means including an aperture, said pin means coupling said connector means, lwhereby said anchoring is provided and said pin means accurately positioning said connector means so that said apertures face towards the planes of the major surfaces of said building panel portion, said pin means projecting outwardly away from said base, whereby said connector means may be quickly coupled to said fastener means and whereby said building panel portion may be removed from engagement with said pin means without objectionably'disturbing the said pin means, together with a longitudinally extending, flexible metallic spacing wire means mounted substantially centrally of the height of said strip, said spacing wire means being bendable in every direction and accurately spacing said connector means of said embeddable metal strand means, said spacing wire means also restraining said. strip from stretching'or contractirngV in length, said spacing wire means being coupled to 'an outer portion of said pin means outwardly from said connector means, whereby said spacing wire means may be positioned after said connector means are positioned and said spacing wire means may be removed while said connector means remain anchored to said fastener means so said spacing wire means may be used elsewherewhile the said building panel vportion is curing? 4 2. A form formolding atleast a portion of-La thin 'oerrientitiousY building panel having stili embeddable metal strand means spaced along at least its edging, said form comprising an elongated elastic strip, a base for lsupporting said strip, said strip being suiciently rigid s0 as to prevent sagging of its top portion when supported on said base, said strip having an effective height substantially equal to [the thickness of said building panel portion to be cast, said strip having a length `at least suiiicient to mold said edging of said building panel portion, said strip being suieiently flexible so as to be bendable in all directions to allow it to follow the contours of curved and at planes, said strip having an offset portion substantially centrally of the height of said strip extending throughout its length and protruding inwardly toward the said building panel portion for molding a keying groove in said edging of said building panel p0rtion, said strip conning the fresh cementitious aggregate of said panel portion deposited onto said base 4and delining its edge shape, said strip having spaced transverse holes through an intermediate portion of its height and substantially parallel to the plane of the said base, said embeddable metal strand means of said building panel portion having end portions extending through said holes, and fastener means disposed along the length of said strip for fastening said strip to said base and for anchoring the said end portions of said embeddable metal strand means, said end portions include connector means, said connector means including an aperture, said vfastener means including pin means supported thereon for coupling said connector means wherein said anchoring is provided, said pin means accurately positioning said connector means so that said apertures face towards the planes of the major surfaces of said building panel portion, said pin means projecting outwardly away from said base, whereby said connector means may be quickly coupled to said fastener means and whereby said building panel portion may be removed from engagement with said pin means without objectionably disturbing said pin means, together with a longitudinally extending, flexible metallic spacing wire means mounted substantially centrally of the height of said strip, said spacing wire means being bendable in every direction and `accurately spacing said connector ymeans of said embeddable metal strand means, said spacing wire means also restraining said strip from stretching or contracting in length, said spacing wire means being coupled to an outer portion of said pin means outwardly from said connector means, whereby said spacing wire means may be positioned after said connector means are positioned, land said spacing wire means may be removed while said connector means remain Ianchored to said fastener means, so that the spacing wire means may be used elsewhere while said building panel portion is curing.

Heltzel Jan. 22, 1935 2,897,668 Graham Aug. 4, 1959 2,971,237 Graham Feb. 14, 196i 

2. A FORM FOR MOLDING AT LEAST A PORTION OF A THIN CEMENTITIOUS BUILDING PANEL HAVING STIFF EMBEDDABLE METAL STRAND MEANS SPACED ALONG AT LEAST ITS EDGING, SAID FORM COMPRISING AN ELONGATED ELASTIC STRIP, A BASE FOR SUPPORTING SAID STRIP, SAID STRIP BEING SUFFICIENTLY RIGID SO AS TO PREVENT SAGGING OF ITS TOP PORTION WHEN SUPPORTED ON SAID BASE, SAID STRIP HAVING AN EFFECTIVE HEIGHT SUBSTANTIALLY EQUAL TO THE THICKNESS OF SAID BUILDING PANEL PORTION TO BE CAST, SAID STRIP HAVING A LENGTH AT LEAST SUFFICIENT TO MOLD SAID EDGING OF SAID BUILDING PANEL PORTION, SAID STRIP BEING SUFFICIENTLY FLEXIBLE SO AS TO BE BENDABLE IN ALL DIRECTIONS TO ALLOW IT TO FOLLOW THE CONTOURS OF CURVED AND FLAT PLANES, SAID STRIP HAVING AN OFFSET PORTION SUBSTANTIALLY CENTRALLY OF THE HEIGHT OF SAID STRIP EXTENDING THROUGHOUT ITS LENGTH AND PROTRUDING INWARDLY TOWARD THE SAID BUILDING PANEL PORTION FOR MOLDING A KEYING GROOVE IN SAID EDGING OF SAID BUILDING PANEL PORTION, SAID STRIP CONFINING THE FRESH CEMENTITIOUS AGGREGATE OF SAID PANEL PORTION DEPOSITED ONTO SAID BASE AND DEFINING ITS EDGE SHAPE, SAID STRIP HAVING SPACED TRANSVERSE HOLES THROUGH AN INTERMEDIATE PORTION OF ITS HEIGHT AND SUBSTANTIALLY PARALLEL TO THE PLANE OF THE SAID BASE, SAID EMBEDDABLE METAL STRAND MEANS OF SAID BUILDING PANEL PORTION HAVING END PORTIONS EXTENDING THROUGH SAID HOLES, AND FASTENER MEANS DISPOSED ALONG THE LENGTH OF SAID STRIP FOR FASTENING SAID STRIP TO SAID BASE AND FOR ANCHORING THE SAID END PORTIONS OF SAID EMBEDDABLE METAL STRAND MEANS, SAID END PORTIONS INCLUDE CONNECTOR MEANS, SAID CONNECTOR MEANS INCLUDING AN APERTURE, SAID FASTENER MEANS INCLUDING PIN MEANS SUPPORTED THEREON FOR COUPLING SAID CONNECTOR MEANS WHEREIN SAID ANCHORING IS PROVIDED, SAID PIN MEANS ACCURATELY POSITIONING SAID CONNECTOR MEANS SO THAT SAID APERTURES FACE TOWARDS THE PLANES OF THE MAJOR SURFACES OF SAID BUILDING PANEL PORTION, SAID PIN MEANS PROJECTING OUTWARDLY AWAY FROM SAID BASE, WHEREBY SAID CONNECTOR MEANS MAY BE QUICKLY COUPLED TO SAID FASTENER MEANS AND WHEREBY SAID BUILDING PANEL PORTION MAY BE REMOVED FROM ENGAGEMENT WITH SAID PIN MEANS WITHOUT OBJECTIONABLY DISTURBING SAID PIN MEANS, TOGETHER WITH A LONGITUDINALLY EXTENDING, FLEXIBLE METALLIC SPACING WIRE MEANS MOUNTED SUBSTANTIALLY CENTRALLY OF THE HEIGHT OF SAID STRIP, SAID SPACING WIRE MEANS BEING BENDABLE IN EVERY DIRECTION AND ACCURATELY SPACING SAID CONNECTOR MEANS OF SAID EMBEDDABLE METAL STRAND MEANS, SAID SPACING WIRE MEANS ALSO RESTRAINING SAID STRIP FROM STRETCHING OR CONTRACTING IN LENGTH, SAID SPACING WIRE MEANS BEING COUPLED TO AN OUTER PORTION OF SAID PIN MEANS OUTWARDLY FROM SAID CONNECTOR MEANS, WHEREBY SAID SPACING WIRE MEANS MAY BE POSITIONED AFTER SAID CONNECTOR MEANS ARE POSITIONED, AND SAID SPACING WIRE MEANS MAY BE REMOVED WHILE SAID CONNECTOR MEANS REMAIN ANCHORED TO SAID FASTENER MEANS, SO THAT THE SPACING WIRE MEANS MAY BE USED ELSEWHERE WHILE SAID BUILDING PANEL PORTION IS CURING. 